<html>
<head>
	<meta charset="utf-8" />
<style type="text/css">
.code{
background-image:url(111.jpg);
font-family:Arial,宋体;
font-style:italic;
color:green;
border:0;
padding:2px 3px;
letter-spacing:3px;
font-weight:bolder;
}
.unchanged {
border:0;
}
</style>
<script language="javascript" type="text/javascript">
var code ; //在全局 定义验证码
function createCode(){ 
code = new Array();
var codeLength = 4;//验证码的长度
var checkCode = document.getElementById("checkCode");
checkCode.value = "";

var selectChar = new Array(2,3,4,5,6,7,8,9,'A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z');

for(var i=0;i<codeLength;i++) {
   var charIndex = Math.floor(Math.random()*32);
   code +=selectChar[charIndex];
}
if(code.length != codeLength){
   createCode();
}
checkCode.value = code;
}

function validate () {
var inputCode = document.getElementById("input1").value.toUpperCase();

if(inputCode.length <=0) {
   alert("请输入验证码！");
   return false;
}
else if(inputCode != code ){
   alert("验证码输入错误！");
   createCode();
   return false;
}
else {
   alert("成功！");
   return true;
}
}
</script>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312"></head>
<body onLoad="createCode();">

<input type="text" id="input1" />
<input type="button" id="checkCode" class="code" style="width:60px" onClick="createCode()" /> <a href="#" onClick="createCode()">看不清楚</a>
<input id="Button1" onClick="validate();" type="button" value="确定" />
<script></script>
</body>
</html>